The present invention describes and enables a self-locking gear. The self-locking gear allows the transfer of rotation and torque from an input shaft to an output shaft while preventing the transfer of rotation or torque from the output shaft to the input shaft.
Various devices are known in the art for locking a gear. For example, one of ordinary skill in the art is familiar with the use of a ratchet and pawl to allow an input shaft to transfer rotation and torque in one direction to an output shaft while preventing the output shaft from rotating in the opposite direction. The disadvantage of the ratchet and pawl is that the output shaft can still rotate independently of the input shaft in at least one direction. In addition, the ratchet and pawl prevents the input shaft from transferring torque or rotation to the output shaft in both directions.
One of ordinary skill in the art is also familiar with the operation and characteristics of a worm gear. A worm gear typically includes a screw in threaded engagement with a gear. Rotation of the screw causes a corresponding rotation of the gear. However, the pitch angle between the screw threads and the gear threads prevents the gear from turning the screw.
U.S. Pat. No. 6,659,429 describes a self-locking reduction device that includes an input shaft (11) and a disc (11d) that is eccentrically connected to the input shaft. A metal sleeve (15) surrounds the disc, and the sleeve connects to an internal gear (24) which in turn connects to the output winding drum (17). A series of pins (16) inserted in bores (10) permit the sleeve to gyrate about the input shaft while preventing the sleeve from rotating with respect to the input shaft. During operation, rotation of the input shaft causes the disc to rotate about the input shaft. The eccentric rotation of the disc causes the sleeve to gyrate in the same direction as the disc. The gyrating sleeve causes the internal gear, and thus the output winding drum, to rotate in the same direction as the input shaft. If torque is applied to the output winding drum, the output winding drum will transfer the torque to the internal gear which will attempt to rotate the sleeve. The pins will prevent the sleeve from rotating in either direction, thus locking the internal gear and the output winding drum.
Based on these and other prior art devices, the need exists for an improved self-locking gear that can transfer rotation and torque from an input shaft to an output shaft while preventing the transfer of rotation or torque from the output shaft to the input shaft.